Electrocardiogram as a predictor of sudden cardiac death in middle-aged subjects without a known cardiac disease

Background: Abnormal 12 lead electrocardiogram (ECG) findings and proposing its ability for enhanced risk prediction, majority of the studies have been carried out with elderly populations with prior cardiovascular diseases. This study aims to denote the association of sudden cardiac death (SCD) and various abnormal ECG morphologies using middle-aged population without a known cardiac disease. Methods: In total, 9511 middle-aged subjects (mean age 42 +/- 8.2 years, 52% males) without a known cardiac disease were included in this study. Risk for SCD was assessed after 10 and 30-years of follow-up. Results: Abnormal ECG was present in 16.3% (N = 1548) of subjects. The incidence of SCD was distinctly higher among those with any ECG abnormality in 10 and 30-year follow-ups (1.7/1000 years vs. 0.6/1000 years, P 100', left ventricular hypertrophy, and T-wave inversions were the most significant independent ECG risk markers for 10-year SCD prediction with up to 3-fold risk for SCD. Those with ECG abnormalities had a 1.3-fold risk (95% CI 1.07-1.57, P - 0.007) for SCD in 30-year follow-up, whereas QRST-angle > 100 degrees, LVH, ER 0.1 mV and 0.2 mV were the strongest individual predictors. Subjects with multiple ECG abnormalities had up to 6.6-fold risk for SCD (P <0.001). Conclusion: Several ECG abnormalities are associated with the occurrence of early and late SCD events in the middle-age subjects without known history of cardiac disease. (C) 2018 The Authors. Published by Elsevier B.V.Peer reviewe

Diabetes, glucose tolerance, and the risk of sudden cardiac death

Background: Diabetes predisposes to sudden cardiac death (SCD). However, it is uncertain whether greater proportion of cardiac deaths are sudden among diabetes patients than other subjects. It is also unclear whether the risk of SCD is pronounced already early in the course of the disease. The relationship of impaired glucose tolerance (IGT) and SCD is scarcely documented. Methods: A general population cohort of 10594 middle-aged subjects (mean age 44 years, 52.6 % male, follow-up duration 35-41 years) was divided into diabetes patients (n = 82), subjects with IGT (n = 3806, plasma glucose = 9.58 mmol/l in one-hour glucose tolerance test), and controls (n = 6706). Results: Diabetes patients had an increased risk of SCD after adjustment confounders (hazard ratio 2.62, 95 % confidence interval 1.46-4.70, p = 0.001) but risk for non-sudden cardiac death was similarly increased and the proportion of SCD of cardiac deaths was not increased. The SCD risk persisted after exclusion of subjects with baseline cardiac disease or non-fatal cardiac events during the follow-up. Subjects with IGT were at increased risk for SCD (univariate hazard ratio 1.51; 95 % confidence interval 1.31-1.74; p <0.001) and also for non-sudden cardiac deaths and non-fatal cardiac events but adjustments for other risk factors attenuated these effects. Conclusions: Diabetes was associated with increased risk of SCD but also the risk of non-sudden cardiac death was similarly increased. The proportion of cardiac deaths being sudden in subjects with diabetes was not increased. The higher SCD risk in diabetes patients was independent of known cardiac disease at baseline or occurrence of nonfatal cardiac event during the follow-up.Peer reviewe

Risk of sudden cardiac death associated with QRS, QTc, and JTc intervals in the general population

BACKGROUND QRS duration and corrected QT (QTc) interval have been associated with sudden cardiac death (SCD), but no data are available on the significance of repolarization component (JTc interval) of the QTc interval as an independent risk marker in the general population. OBJECTIVE In this study, we sought to quantify the risk of SCD associated with QRS, QTc, and JTc intervals. METHODS This study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up period was limited to 10 years and age at baseline to 30-61 years. QRS duration and QT interval (Bazett's) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc interval - QRS duration. Cox proportional hazards models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD. RESULTS During a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio [HR] 1.030 per 1-ms increase; 95% confidence interval [CI] 1.017-1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007; 95% CI 1.001-1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001; 95% CI 0.996-1.007). CONCLUSION Prolonged QRS durations and QTc intervals are associated with an increased risk of SCD. However, when the QTc interval is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.Peer reviewe

Risk of sudden cardiac death associated with QRS, QTc, and JTc intervals in the general population

BackgroundQRS duration and corrected QT (QTc) interval have been associated with sudden cardiac death (SCD), but no data are available on the significance of repolarization component (JTc interval) of the QTc interval as an independent risk marker in the general population.ObjectiveIn this study, we sought to quantify the risk of SCD associated with QRS, QTc, and JTc intervals.MethodsThis study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up period was limited to 10 years and age at baseline to 30–61 years. QRS duration and QT interval (Bazett’s) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc interval – QRS duration. Cox proportional hazards models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD.ResultsDuring a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio [HR] 1.030 per 1-ms increase; 95% confidence interval [CI] 1.017–1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007; 95% CI 1.001–1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001; 95% CI 0.996–1.007).ConclusionProlonged QRS durations and QTc intervals are associated with an increased risk of SCD. However, when the QTc interval is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.</p